The present invention relates to a bowed, external, spring retaining ring and to a method of making same.
Machines, tools and numerous other types of structures and equipment include separate components which are to be secured in place. Use is often made of spring retaining rings which are mounted in one component to form an artificial stop shoulder in the path of the other component or retained part Retaining rings can be of various types. One type of retaining ring is a so-called "bowed" ring which is of non-planar (non-flat) profile (e.g., see U.S. Pat. No. 2,487,802). Such a bowed ring is yieldable resiliently in an axial direction and thus is highly suited for taking up end play caused by component wear and/or tolerances in groove location or dimensions of the components, and also to dampen vibrations and oscillations, among other uses. In addition, bowed rings maintain a tight grip radially against the bottom of the groove.
Bowed retaining rings can be of the "internal" or "external" type. An internal ring is specifically configured and dimensioned so that its outer periphery fits into a circular internal groove of one component and its inner or bowed periphery lies in the path of the retained part to be capable of making contact with the latter. Thus, an internal bowed ring engages the retained part with its convex side.
An external ring is specifically configured and dimensioned so that its inner periphery fits into a circular external groove of one component and its outer periphery lies in the path of the retained part to be capable of making contact with the latter. Thus, an external bowed ring engages the retained part with its concave side (FIG. 4).
Bowed external spring rings can be of various configurations, such as a so-called E-ring which includes a middle prong. The middle prong projects radially inwardly from the middle section of the ring. Installation of such an E-ring is performed in the radial direction, i.e., by sliding the ring radially into the groove.
Bowed external retaining rings can be formed by various techniques, including punching. A punching operation which has heretofore been employed involves the use of a punch 1 of the type depicted in FIGS. 1-3. That punch has a shank 2 formed in the shape of the ring. The end 3 of the shank is convexly curved in a configuration corresponding to the bowed curvature to be formed in the ring. One characteristic of rings 4 (FIG. 5) formed in that manner is that the leading edge 10 and trailing edge 11 of the concave side of the ring (FIG. 4) are sharp. That is, an edge of the ring formed by contact of leading and trailing edges 5, 6 of the punch with the metal blank is sharp in nature, due to the known, inherent characteristics of a punching operation. Since the concave side of the ring faces the retained part 14, the sharp edges 10, 11 may tend to dig into that part not only after the ring has been installed, but during installation as well. That is, a bowed external ring of E-shape is installed in a radial direction 18 whereby the leading edge 10 of the ring concave side slides along the surface 20 of the retained part 14 and tends to dig into such surface 20, and also possibly into a surface 21 of the groove of the other component 16. Such scoring is especially prevalent in the case of components formed of a relatively soft material such as aluminum for example. Scoring of a component can produce serious problems, such as the creation of burrs and/or loose bits of metal which may interfere with proper operation.
In bowed rings which are not of an E-shape and which are installed in an axial direction, rather than a radial direction, the existence of a sharp leading edge on the ring does not pose the problem discussed above.
Disadvantages associated with sharp ring edges have been noted for example in British Pat. No. 660,746 published Nov. 14, 1951. In FIGS. 5-6 of that patent a bowed external spring retaining ring of the E-shape type is disclosed in which the leading and trailing ends of the ring have been flattened in order to reduce contact of sharp edges with the retained part. While there is no disclosure in that British patent of the exact manner in which the rings are to be formed, the ring formation results in the creation of sharp edges on the concave side of the ring, the disadvantages of which are to be reduced by the provision of the flats. It appears that while the provision of flats at the leading and trailing ends of the ring may diminish to some extent the scoring problem, the problem is not completely eliminated especially during the installation of the ring in which a sharp leading edge, even when disposed on a flattened portion of the ring, will tend to score the retained part.
Of course, the rings can be machined after fabrication and prior to installation in order to smooth-out the sharp edges, but such a procedure is highly impractical from time and economical standpoints.
It is further noted that the flattening of the trailing end of the ring in the British patent is achieved to such an extent that even the middle prong of the ring is flattened. Flattening of the ring to that extent will considerably reduce the length of the bowed portion and thus will unduly stiffen the ring and adversely affect its performance.
It is, therefore, an object of the present invention to minimize or obviate problems of the type discussed above.
Another object is to provide a bowed external spring retaining ring of the E-shaped type which does not present a sharp leading edge along the concave side of the ring and which is not excessively stiff.
A further object is to provide an inexpensive method of manufacturing such rings whereby at least the leading edge of the ring along the concave side of the ring is rounded.
An additional object is to provide such a method which involves punch-forming and wherein the rounding of leading edge is achieved inherently by the punching operation itself.